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In the paper, the impact of paper production waste (primary sludge, or PS) on the properties of cement pastes and mortars is discussed upon. Some specimens were formed with fine PS fraction that replaced a part of cement content in them (5%, 10%, 15%, or 20%); in other specimens, coarse fraction of sludge (2/4) was used and a part of content of fine filler (sand) was replaced by PS. The properties of mixtures, such as water content required for cement paste of normal consistence, the setting time, exothermic temperature, flow diameter and plunger penetration, were established. In addition, the properties of hardened mortar, such as its density, flexural strength and compressive strength, were established. The microstructure of hardened specimens was examined as well. It was found that PS retarded hydration processes and reduced exothermic temperature; in addition, it reduced the flow diameter and the plunger penetration. While assessing the properties of hardened mortar, it may be stated that 5% PS waste might be used for replacement of a part of cement content. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents results of an investigation into the potential use of recycling paper mill waste-water to replace mixing water in cement mortar systems for manufacturing concrete masonry products. The physical and mechanical properties of mortar containing various amounts of de-inking waste-water were consequently investigated. A key finding of this study was that replacing mortar mixing water with waste-water significantly improved workability and consistency of cement mortar mixtures. In particular the flow of mortar mixtures increased with increase of waste-water content up to 50% and then levelled off when waste-water content exceeded 50%. Correspondingly, the flow of mortar mix with 100% waste-water replacement at water/cement ratio of 0.50 was found to be equivalent to that of the reference mortar mix with 100% potable water at water/cement ratio of 0.60, indicating potential use of de-inking waste-water as water reducing admixture. The enhanced workability arising from waste-water addition however induced changes in mechanical properties of the hardened material. Compared to reference mortar, replacing 10% and 100% potable water respectively resulted in 19% and 60% reduction of compressive strength, with a corresponding 5% and 16% drop in bulk density, and up to 19% increase in drying shrinkage. Also, water absorption and volume of permeable voids increased with increasing waste-water dosage, albeit marginally. The benefits derived from rheology improvements compared to compromises in mechanical properties due to de-inking waste-water addition strongly indicate clear potential of using de-inking waste-water in production of lightweight cementitious building and masonry elements. [Copyright &y& Elsevier]

Highlights: [•] APS-FA blended cement mortars showed good resistance to freeze/thaw cycles. [•] Blended mortars perform better than OPC mortars in marine environments. [•] Resistance of blended and OPC mortars to Spanish’s plateau conditions are similar. [ABSTRACT FROM AUTHOR]

Abstract: Making use of industrial by-product or waste clay to partially replace cement in concrete has greatly contributed to sustainable development of environment. This study investigated the optimal activation condition for producing high reactivity metakaolin (MK) by using kaolin by-products (KB) from paper industry. Initially, the material properties of KB were analyzed in this study and the results indicated its great potential to be treated by calcination to be a very effective pozzolan. Afterwards, MK samples produced from different activation treatments of KB, including different calcining temperature, calcining duration, initial temperature rise rime and grinding particle size, were applied in mortar to determine their pozzolanic effect. Results indicated that the optimal activation condition for KB to high reactivity MK conversion is 2-h calcining duration at 750°C and with 7μm grinding particle size. Finally, compressive and flexural strengths of mortar samples produced by replacing cement with 0–25% MK content were tested and the results showed that 15% was the optimal cement replacement level of MK and the mortar so produced exhibited 20% improvement in compressive strength compared to control mortar. [ABSTRACT FROM AUTHOR]

Highlights: [•] A beneficial reuse application for two industrial wastes, EPS and PSA, is reported. [•] Lightweight cement mortars containing PSA and EPS have low density and low thermal conductivity. [•] Ground EPS resulted in lower thermal conductivity than powdered EPS. [•] Mortars containing EPS and PSA meet the EU standards for rendering, masonry and plastering. [ABSTRACT FROM AUTHOR]

• Calcareous sludge is used as filler in geopolymeric mortars. • Biomass fly ash is used as main alumina-silicate source (70 wt%). • Used wastes derive from a Kraft pulp industry. • Manufacture is simple and highly sustainable and reproducible. • Novel geopolymeric mortars are suitable for construction applications. Calcareous sludge is an alkaline waste produced by the paper pulp industry that is commonly disposed of in land-fill. However, recent studies and the European regulations discourage such practice. This work investigates an alternative and innovative way to recycle and reuse this waste, as filler, in the production of green geopolymeric mortars intended for applications in construction. This is the first time that this calcareous sludge is used to produce novel waste-based materials, in both construction and geopolymer technology. The novel alkali-activated mortar also uses biomass fly ash – another slightly investigated waste stream – to substitute the metakaolin (70 wt% substitution) and the manufacture process is performed at ambient conditions. All of that reduces the overall process footprint. The implemented mix design is aimed at maximising the waste incorporation and improving the material properties, such as workability and mechanical performance. The main results demonstrate that 10 wt% of calcareous sludge can be efficaciously used as filler in the geopolymeric mortars, generating up to 30% improvement in the mechanical resistance. This alternative use of such wastes will contribute to increase the sustainability of the novel construction materials also granting environmental advantages and a financial surplus for the industry. [ABSTRACT FROM AUTHOR]

• A method for batch calculation of aggregate shape parameters was proposed based DIP. • The numerical model of mortar fluidity test was successfully established by DEM. • The increase in flake particle content leads to greater elongation of machined sand. • High flaky particle content can lead to poor flowability of mortar. • There is a correlation between the aggregate shape parameters and the fluidity. This paper combined digital image processing (DIP) and discrete element method (DEM) to investigate the relationship between the particle characteristics of manufactured sand and the flow ability of mortar, and clarified the key characteristics parameters of particle shape influencing the flow ability of mortar. A method for batch calculation of shape characteristic parameters (elongation n e , angularity index n a and fullness ratio n f) of aggregates based on DIP was proposed. The fluidity tests and corresponding simulations of mortar at different water-cement ratios were carried out respectively, and the results showed that the errors of simulated fluidity (f m) were around 7%. The simulation results demonstrated that the f m decreased with increasing content of large-size aggregates in the mortar. The augment of both n e and n a reduced the flowability of mortar. The magnitude of rolling/sliding friction coefficients of aggregates are the important parameters that determine the flowability of mortar. [ABSTRACT FROM AUTHOR]

This paper studies the effect of high temperatures (20℃, 200℃, 400℃, and 600℃) and stress ratios ( σ 2 / σ 3 ) (0.15, 0.3, 0.45, and 0.60) on biaxial compressive strength and strain development patterns of high-strength geopolymer concrete (HGPC). Experimental observations indicate that HGPC exhibits laminar damage similar to ordinary Portland concrete (OPC) before and after exposure to high temperatures, under biaxial compression. Unlike OPC, damage in HGPC initially passes through coarse aggregates at room temperature but shifts predominantly to the aggregate-mortar interface at 600℃. The biaxial compressive strength envelope of HGPC expands with rising temperatures. The increased multiple of biaxial compressive strength ( σ 3 / f m ) for HGPC at room temperature rises and then falls with increasing stress ratios, peaking at a stress ratio of 0.45 and surpassing the values for OPC and high-strength concrete (HSC). Before high temperature, the modulus of elasticity of HGPC is higher than that of OPC and decreases with increasing temperature, decreasing by about 45–60% for every 200°C increase, and the reduction is greater than that of OPC. The existing failure criterion is not suitable for HGPC after high temperature, this paper develops a new biaxial compression failure criterion for HGPC before and after high temperature based on Kupfer's criterion, taking into account the effect of temperature. The proposed failure criterion calculation results are well in agreement with the experimental data. A damage constitutive model for HGPC considering the effect of temperature and lateral pressure is also proposed, combining the Weibull distribution model for the ascending branch and a modified empirical model for the descending branch. This combined model effectively predicts the stress-strain relationship of HGPC under various temperature conditions. • The axial behavior of HGPC is tested at different temperatures and lateral pressures. • A failure criterion for biaxial compression of HGPC taking into account the effect of temperature is proposed. • A damage constitutive model of HGPC considering the effect of temperature and lateral pressure is established. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the variation rule of coarse aggregate and pore structure of shotcrete by adding MWCNTs. In the paper, X-ray computed tomography scans are used to study the coarse aggregate distribution and pore structure of the preparation of shotcrete, high-temperature curing shotcrete and shotcrete with MWCNTs. The distribution pattern of coarse aggregate and pore of shotcrete is obtained. The results show that: the coarse aggregate loss of shotcrete is serious within 30 mm from the wall and the coarse aggregate increases significantly in 30–70 mm. The addition of 0.03% MWCNTs increased the coarse aggregate of shotcrete by 36.63% and the volume of coarse aggregate by 25.64%. The largest increase is in coarse aggregates of 5–7 mm. This show that MWCNTs can improve mortar adhesion and reduce aggregate rebound. The number of shotcrete pores decreases with the increase of pore diameter. The proportion of small pores is up to 85%, the proportion of large pores is only 2%, but the volume of large pores reaches 87%. The addition of 0.03% MWCNTs can reduce the number of small pores in the shotcrete and reduce the mean pore diameter, resulting in a decrease in the porosity of the shotcrete. When the curing temperature is 80℃, the porosity of shotcrete increases, and the pores decrease due to interconnection. The pores around the coarse aggregate account for over 70% of the total porosity, with pores larger than 1 mm accounting for 75%. This paper has a good reference value for the development of shotcrete and the selection of coarse aggregate in the actual working conditions. • The coarse aggregate distribution and pore structure characteristics of shotcrete were revealed. • The influence of MWCNTs on the rebound of shotcrete coarse aggregate was analyzed. • The relationship between pore distribution of shotcrete and coarse aggregate distribution is discussed. [ABSTRACT FROM AUTHOR]

Utilizing nano-SiO 2 (NS) to reinforce the old mortar and the weak interfacial transition zone (ITZ) in recycled coarse aggregate (RCA) is a productive approach to enhance the quality of RCA. Throughout this paper, RCA was immersed in NS solutions with different concentrations (2, 5, 10 and 30 wt%). Subsequently, a systematic evaluation of the crushing index and water absorption of the treated NS modified recycled coarse aggregate (SRCA) was conducted. In addition, the calcium hydroxide (CH) content of RCA before and after modification was analyzed by Thermogravimetric and Differential Thermal Analysis (TG-DTA) curves. This study finds that the performance of SRCA modified with 2% concentration achieves comparable modification effects to other concentrations. Additionally, this paper delves into the impact of NS powder on the slump characteristics and compressive strength of concrete. Considering the above research and economic costs, this study adopts 2% concentration of NS for RCA modification and further investigates the stress-strain relationship of NS modified recycled aggregate concrete (SRAC) with various SRCA replacement ratios. Moreover, this paper establishes mesoscopic models of SRAC for various replacement rates and proposes constitutive models corresponding to these rates. The results indicate that when the SRCA replacement rate is within 60%, the stress-strain curve shape of SRAC closely resembles that of natural aggregate concrete (NAC); when the replacement rate exceeds 60%, the descending segment of the SRAC stress-strain curve becomes more precipitous, showing a higher tendency towards fragility in the concrete. ● Nano-SiO 2 can be used to improve the properties of recycled coarse aggregates. ● NS powder affects the slump and compressive strength of recycled concrete. ● As the concentration of NS solution increases, the compressive strength of concrete increases. ● Mesoscopic models of modified recycled concrete were established and constitutive models were proposed. [ABSTRACT FROM AUTHOR]

Since 3D printed concrete has a promising application in engineering, the combination of 3D printing concrete and other building materials has become a hot research topic.This paper investigates the shear properties of 3DPM-NM specimens which use 3D printed mortar (3DPM) as the precast part and normal mortar(NM) as the cast-in-place part. Four different types of interfacial locking design were analyzed in this paper, including L-shaped, C-shaped, S-shaped and K-shaped. The shear damage law of the specimens was analyzed using digital image correlation (DIC) technology. The results show that L-shaped specimens are basically damaged along the shear surface during the loading process. Most of the initial cracks in the C-shaped, S-shaped and K-shaped specimens appeared along the interfacial bonding surface during the loading process. Then, the cracks in the C, S and K-shaped specimens continued to develop along the interfacial bonding surface or spilt through the specimens directly. The results show the shear properties of the C-shaped specimens are similar to those of L-shaped specimens. And the mechanical properties of S-shaped and K-shaped specimens are better than those of L-shaped specimens which increased by 96% (S-shaped), 78% (K-shaped) respectively. The mean slip is increased by 10% in S-shaped specimens and 28% in K-shaped specimens compared with that of L-shaped specimens. According to the AASHTO GSCB INTERIM-2003 specification, the modified formula for the shear bearing capacity of 3DPM-NM specimens is proposed in this study. The calculated resultsare in good agreement with the test results, which theoretically provide guidance for the application of 3DPM, lay the foundation for its feasibility as a structural body of a building. • Specimens with 3D printed mortar (3DPM) as a precast component and normal mortar(NM) as a cast-in-place part were tested. • Comparison of the shear performance of specimens with different types of interfacial locking design were conducted. • Theoretical analysis and modified calculations of shear strength for 3DPM-NM interfacial locking specimens were carried out. [ABSTRACT FROM AUTHOR]

In this paper an overview is presented on the use of diatomaceous earth (DE) as a partial substitute for binder and fine aggregate in mortars. For this purpose, this paper was divided into two sections. In the first one, concepts related to physical, chemical and microstructural properties of DE, as well as results of previous studies about its reactivity used in different construction materials (cement, concrete, mortar, bricks, phase change materials etc.) were summarized and discussed. In the next section, the effects of using DE on the fresh, hardening and durability properties of cement and lime-based mortars were discussed. In general, the results suggest that increasing DE content may reduce mortar performance due to the high porosity of its particles. However, this deficiency was observed for DE contents higher than 20%, which, however, can be compensated for by using superplasticizer additives or by volumetric dosage instead of by weight one. This critical value of up to 20% of DE was calculated using T2 statistical on the scores of principal components analysis obtained from the results collected from publish manuscripts. Nevertheless, the results of this review research may contribute to provide information on an under-explored alternative source of supplementary cementitious materials (SCMs) and therefore help mitigate the negative effects generated by the cement industry and assist in the production of mortars with a lower carbon footprint that can play an important role in the thermal behavior of buildings. • State of the art systematic review of diatomaceous earth (DE) for mortar production. • Statistical analysis of the mechanical properties of mortar with DE. • Understanding the effects of DE on properties of mortars. • When up to 20% DE is used, the mechanical behavior of mortars can be improved. • Paths for the development of new studies on mortars incorporating DE are shown. [ABSTRACT FROM AUTHOR]

To address the challenge posed by traditional methods of modifying recycled concrete aggregates (RCA), which struggle to achieve properties comparable to natural coarse aggregates (NCA) while ensuring a high utilization rate, this paper proposes a combination of freeze-thaw modification and sodium silicate modification. The process subjects the RCA to freeze-thaw cycles (FTC) to detach the attached mortar, which results in the extraction of recycled aggregates (Near-NCA) with properties similar to NCA, along with the spalling mortar (SM). These materials are used in the recycled concrete and mortar, respectively. Considering the inferior properties of SM, sodium silicate solutions are employed to modify it, serving as a replacement for river sand in the recycled mortar. The outcomes reveal that concrete cast using Near-NCA demonstrates mechanical properties comparable to ordinary concrete. Furthermore, the sodium silicate proves to be effective in modifying SM, reducing its crushed index and water absorption by approximately 30%. Through the SEM and XRD, it is determined that these improvements can be attributed to the formation of C-S-H gel. Finally, a multi-objective model is developed to consider modification effects, carbon emissions, energy consumption, economic and time costs, with the utilization of TOPSIS for determining the optimal modification plan. • This paper proposes a method that combines freeze-thaw modification with mineralization strengthening. • Modifying spalling mortar with sodium silicate solution can improve its various properties. • The modification mechanism of sodium silicate is investigated through microscopic tests. • The TOPSIS method is utilized to obtain the optimal modification scheme considering multiple objectives. [ABSTRACT FROM AUTHOR]

The hydrophobicity nature of the waste carbon fiber felt (WCF) surface results in the formation of a weak interface with the paste during the curing process of WCF concrete, which seriously affects the performance of WCF concrete and the reuse of WCF. To address this problem, this paper utilized polydopamine (PDA) for the functionalization of WCF to enhance bonding between WCF and paste. The wettability, Ca2+ complexation, and functional groups of PDA coating on WCF were analyzed by contact angle, ICP-OES, and XPS, respectively. Additionally, the effects of incorporating PDA-functionalized WCF on the flowability, compressive strength, hydration kinetics, pore structure, water absorption capillary, and SEM of mortars were tested. Experimental results showed that the PDA coating improved the wettability of WCF and enhanced the flowability of WCF mortar. What's more, the PDA coating could chelate Ca2+ and promote the formation and deposition of hydration products on the WCF surface, resulting in a denser interfacial transition zone (ITZ). Compared with ordinary WCF mortar, the compressive strength of the PDA-modified WCF mortar was increased by 18% at 28d. Furthermore, the capillary water absorption of the modified group mortar was also decreased by up to 13%, significantly enhancing the durability of mortars. This paper presents a green and simple bio-inspired method to strengthen the ITZ between WCF and paste, which is fundamentally different from the traditional modification methods, and also offers a theoretical basis and technical foundation for the sustainable utilization of WCF. • Introducing hydroxyl and amino groups on WCF using PDA. • The contact angle of WCF was maximum decreased to 40.49°. • The interface gap of WCF/paste was enhanced owing to the chelation of PDA with Ca2+. • The compressive strength of WCF mortars modified by PDA was improved from 39.43 MPa to 46.52 MPa at 28d. [ABSTRACT FROM AUTHOR]

Mesoscale modelling is a promising tool to analyse the phenomenological causes of mechanical failure of recycled aggregate concrete (RAC). Most mesoscale models of RAC are two-dimensional (2D) and 3D models are lacking. This prevents the full understanding of the behaviour of each mesoscopic phase. This paper presents a 3D model of RAC and analyses its mechanical behaviour based on mesoscale phenomena. The analyses concern three types of tests carried out in concrete specimens: uniaxial compressive, uniaxial tensile and splitting tensile strength tests. The mechanical response and fracture behaviour of each mesoscopic phase is analysed in relation to the response of RAC specimen. The comparisons between uniaxial behaviour of 3D and 2D modelling as well as between uniaxial and splitting tensile behaviour of RAC are presented. The main findings of the paper are: (1) the full curve of uniaxial stress-strain response from 3D modelling is comparable to that from 2D modelling for RAC (therefore, 2D models are validated for RAC modelling); (2) the overall behaviour of the concrete elements remains elastic regardless of the fracture development in the ITZ and attached mortar of recycled aggregates until damage propagates to the new mortar matrix; (3) a relationship between modelled uniaxial and splitting strength of RAC is established and validated. [Display omitted] • Realistic mesostructural model of RAC - particle size, attached mortar content and ITZ with real thickness. • Replicate the strength test of uniaxial compression, uniaxial tension, and splitting tension. • Validate the use of 2D model through comparison of the outcomes from 2D and 3D models. • The influence of each mesoscopic phase on the overall mechanical behaviour of RAC. • Establish the relationships between the modelled uniaxial and splitting tensile strength. [ABSTRACT FROM AUTHOR]

• LSS used as a NS substitute in FA/GGBS-based mortar increases compressive strength. • GO-modified mortars show superior viscosity recovery to NC-modified ones. • LSS mortars offer higher strength and lower drying shrinkage than NS mortars. • Formwork-free conditions increase drying shrinkage in 3D printed mortars. • High temperature & humidity reduce drying shrinkage in printed GO/NC modified mortar. The environmental impact of concrete 3D printing (C3DP) has become a concern due to its large cement consumption and over-exploitation of natural resources. This study investigates the viability of using geopolymer mixtures in C3DP prepared with fly ash (FA)/ground granulated blast furnace slag (GGBS) and underutilised aggregate as substitutes for ordinary Portland cement (OPC) and natural aggregate, respectively. This paper focuses on the rheological, mechanical, and shrinkage properties of FA/GGBS-based geopolymer mortar with lead smelter slag (LSS) as natural sand (NS) substitute and the impact of adding nanoclay (NC) and graphene oxide (GO), as thixotropy agents, on the yield stress development and viscosity recovery properties of the mixtures. The effect of various outdoor environmental conditions of 24 °C -50 %RH, 35 °C -90 %RH and 35 °C -50 %RH on pore water evaporation and 28-day drying shrinkage of 3D printable geopolymer mortar was studied, considering the effect of NS, LSS, NC and GO in free-formed and control conditions. LSS GO-modified mortars exhibited superior viscosity recovery capacity and yield stress evolution compared to their NC-modified counterparts. Moreover, using LSS instead of NS resulted in increased 28-day compressive strength under various environmental conditions, and LSS mortars exhibited lower drying shrinkage in both conventional casting and free-formed conditions. The findings of this paper will serve as a benchmark for further studies on the effect of different curing techniques (internal or external) on the hardened state dimensional stability of 3D printed products using alkali-activated binder systems to improve the structural integrity by controlling the water evaporation and drying shrinkage development. [ABSTRACT FROM AUTHOR]

This paper presents an innovative hierarchical meta-modelling approach for predicting the effective elastic properties of stone injected with composite cement grouts containing Carbon NanoTubes (CNTs) for structural rehabilitation purposes. The study first addresses the homogenization of the nano- and micro-scales through numerical representative volume elements. The first numerical model focuses on the cement matrix doped with randomly oriented CNTs, while the second model represents the porous stone with CNT/cement grout filling the pores. However, the computational burden associated with these models poses a significant limitation when analysing large-scale macrostructural elements. To overcome this challenge, a hierarchical meta-modelling approach based on two nested Kriging surrogate models is proposed. This approach offers a fast and accurate alternative to bypass the time-consuming numerical homogenization process. The first surrogate model establishes a connection between the microstructural characteristics of the CNTs and cement and the effective elastic properties of the composite grout. Subsequently, a second meta-model expands over the first one by introducing two additional variables: the elastic modulus of the stone and the porosity, allowing for estimation of the overall elastic properties of CNT/cement/stone composites. The accuracy and efficiency of the proposed hierarchical meta-model is demonstrated through detailed parametric analyses. To showcase its potential for optimizing rehabilitation interventions, the paper is closed with its application to a benchmark case study of a stone column injected with CNT/cement grout. • Composite CNT/cement grouts are investigated for the first in the literature. • A novel nested surrogate modelling approach is proposed for multi-scale composites. • Fast stiffness estimates of porous stone injected with CNT/cement grout are obtained. • The proposed approach is used to assess the performance of grout injected columns. [ABSTRACT FROM AUTHOR]

• Pumpability and buildability of Portland cement/GGBS binders presented. • Pumpability correlates with w/b ratio, whereas buildability with w/b ratio and printing speed. • Process of crack formation presented to provide insights into structural behaviours of 3D printed arch truss. • Estimation of tensile strength of 3D printed truss elements should consider restrained shrinkage effects. • Potential of GGBS for reducing the embodied carbon of 3DP cementitious binder highlighted. The work presented in this paper forms part of a wider research programme being undertaken on the development of low-carbon cementitious mortars for 3D printing applications. Specifically, this paper investigates the potential of ground granulated blast-furnace slag (GGBS) as a partial replacement for Portland cement. Five mortar mixes with varying water/binder (w/b) ratios (0.35 to 0.45) were tested, and to investigate their pumpability and buildability, a series of wall-like specimens were printed using a custom-built 3D printer under a range of speeds of 2 to 4 m/min. Pumpability was found to be directly related to w/b ratio, whereas buildability was found to be dependent upon both test parameters. Mortar mixes with w/b ratios in the range 0.37 to 0.40 demonstrated promising pumpability and buildability characteristics when extruded at the optimum printing speed of 2.5 m/min. Moreover, to demonstrate the application of the optimised mix, an arch truss prototype was printed and subsequently tested to failure to provide insights into the structural behaviour of a 3D printed arch truss member. From the process of crack formation and accompanying analysis, it was found that although the development of tensile stresses in the 3D printed prototype was minimal (a direct result of the arch geometry), it still governed the overall member behaviour due to the presence of internal stresses induced by restrained shrinkage. [ABSTRACT FROM AUTHOR]

• The morphologies of aggregates can be quantified using photography and processed through ImageJ. • The number of aggregates and volume of mortar in an asphalt mixture is enough to predict its porosity, stiffness, stability, and flow. • New design models enable to select optimal aggregate's number and mortar's volume to achieve desired performance of asphalt mixtures. • New design models help checking whether one asphalt mixture fulfils performance requirements. Conventional asphalt mix design methods require numerous experiments to verify the efficacy of various recipes, resulting in significant time and labour costs. Therefore, there is a need for an alternative method that is both efficient and convenient. To address this issue, this paper proposes a novel asphalt mix design method that reduces the reliance on time-consuming and resource-intensive physical and mechanical tests to determine the properties of new asphalt mixtures. The method focuses on the quantity of aggregates and the volume of mortar to estimate the air voids content, resilient stiffness modulus, Marshall stability, and flow requirements in accordance with industry standards. Statistical analysis shows that the key properties of asphalt mixtures are primarily influenced by the number of aggregates and volume of mortar. Nomographs are provided to predict these properties based on the mixture's gradation and mortar volume. The proposed method's feasibility is demonstrated by accurately predicting the gradations and properties of six different mixtures. Additionally, the paper suggests the use of 3D models for asphalt mixtures, allowing for the observation of aggregate distribution and air voids before testing the mixtures' mechanical properties. [ABSTRACT FROM AUTHOR]

• TRs and RG were co-treated to produce a new blended binder with good mechanical strength and water resistance. • RG and CRG can effectively activate the hydraulic property of TRs by electrodeless resistivity test. • This paper provides a cost-effective method to recycling TRs and RG. The huge accumulations of Ti-extracted residues (TRs) and red gypsum (RG), which are the solid by-products from TiO 2 pigment industry, have caused a series of on-site and off-site environmental problems. This work is concerned with the feasible recycling of TRs, RG, calcined RG (CRG) as main components in the production of a novel cementing material. The resulting mechanical strength, softening coefficient, hydration behavior (electrical resistivity) and microstructure (porosity and hydration products) of this binder were investigated. It was found that the flexural strength, compressive strength and softening coefficient of mortar samples at 28 days can reach up to 6.3 MPa, 47.9 MPa and 0.87, respectively. An electrodeless resistivity test, over a period of 72 h was also conducted: an increasing content of RG from 0 to 40% retarded the hydration within the first 24 h, whereas both the binders incorporating 20% CRG plus 20% RG and 40% RG were responsible for the later accelerating hydration. Moreover, an increase of RG's content (from 10% to 40%) and the substitution of CRG for RG decreased total porosity and narrowed pore size distribution of mortar samples. Results from X-ray diffraction and morphology analysis revealed that the intertwined hydrated products in the hardened binders were needle-like ettringite, unreacted bar-like gypsum and filamentous C-(A)-S-H, ensuring the blends with a good water resistance. In summary, this paper provides a cost-effective approach for utilizing TRs and RG to produce a high-strength cementing material as an alternative to ordinary Portland cement. [ABSTRACT FROM AUTHOR]

• This paper investigated the performance of mortars containing steel scale. • Taguchi based grey relational analysis method was applied in this study. • Water/cement ratio was found the most important parameter on the responses. • The addition of scale has improved mechanical strengths and porosity of the mortars. This paper examined the performance of cement mortars containing steel scale as experimentally and statistically. To this end, mortar samples with different levels of fine scale (0%, 5%, 10%, 15%), coarse scale (0%, 5%, 10%, 15%), water/cement ratio (0.5, 0.6) and cement dosage (400 kg/m3, 500 kg/m3) were produced and their compressive strength, flexural tensile strength and porosity value were determined. Taguchi based grey relational analysis method was performed to obtain optimal parameter levels for simultaneously achieving the desired properties of the mortars. L 16 (42 × 22) orthogonal array table was chosen for the tests according to the Taguchi quality design concept. ANOVA (Analysis of variance) method was applied to determine statistically effects of the parameters. Optimization results were compared with initial parameters (control sample) and it was concluded that there was a good fit between them. Based on the overall observations, it is recommended that the Taguchi based grey relational analysis method could be effectively used in such studies. [ABSTRACT FROM AUTHOR]

Highlights • Shrinkage and expansion of various glass aggregate mortars are presented in this paper. • Crushed glass, glass beads, and expanded glass were used to replace natural sand. • Crushed glass and glass beads in mortar improved plastic and drying shrinkage. • Mortar bar tests confirmed deleterious nature of glass, except for expanded glass. Abstract This paper presents the effect of various glass aggregates on plastic and drying shrinkage and alkali silica reaction (ASR) expansion of cement mortar. The study was done by substituting a portion of sand with expanded glass, crushed glass, and glass bead aggregates. The low absorption capacity of glass, except expanded glass, enhanced the dimensional stability of the mixtures, minimizing volumetric contraction associated with shrinkage. Presence of finer glass particles in the mortar resulted in a large benefit in ASR expansion. The study found that cement mortar with glass aggregates can be beneficial if aggregate type and amount is chosen appropriately. [ABSTRACT FROM AUTHOR]

Highlights • The cracking behavior of cementitious materials can be monitored by EIS. • The semi-circle in Nyquist plot is present in the cracked mortar at high frequency, • R ct in Nyquist plots, Z and θ° in Bode plots sensitively reflect the cracking behavior. • The stability and smoothness (fluctuation) of Bode plot can response the cracking degree. Abstract In this paper, electrochemical impedance spectroscopy (EIS) is used as a non-destructive testing method for investigating the cracking behavior of two kinds of cement-based materials with/without fiber, which are engineered cementitious composites (ECC) and plain mortar. The experimental results show that the cracking patterns and deflection-load curves of plain mortar and ECC are different when the external load reaches to the first-cracking load and ultimate load. The EIS results show that the parameter value of R ct and plural modulus value Z in fractured mortar increase several hundred times compared with correspondingly origin plain mortar. Moreover, the semi-circle presents in the fractured mortar at high frequency and the diagonal lines are deviated from less than 45 deg at low frequency, and the phase angle (θ°) in cracked mortar decreases as the frequency decreases in Bode plots. However, the values of R ct and Z in cracked ECC increase dozens of times compared to origin ECC, and the phase angle decreases as the frequency decreases. The variation of R ct in Nyquist plots, and the stability and smoothness of Bode plot sensitively reflect the cracking degree of cementitious system. In this paper, it is proposed that as a non-destructive method, electrochemical impedance measurement can be used to evaluate the cracking behavior of cement-based materials. [ABSTRACT FROM AUTHOR]

Highlights • Brick masonry blocks were reinforced with FRCM composites. • Two different mortar matrices (natural hydraulic lime and Portland cement) were used. • Wetting-drying cycles in water and saline solution were carried out. • The bond behavior of FRCM-masonry joints and the materials deterioration were investigated. • The matrix played a key role in the debonding mechanism and in the salt crystallization pattern. Abstract Fiber-reinforced cementitious matrix (FRCM) composites are a new category of composites recently proposed for seismic strengthening of historical masonry structures, to provide a more compatible solution compared with fiber-reinforced polymer (FRP) composites. Despite the rapidly increasing number of research papers dealing with the mechanical behavior of FRCM composites applied to masonry, their long-term performance and susceptibility to weathering processes are still largely unexplored. In this paper, the response of FRCM-masonry joints to accelerated weathering is investigated. A laboratory testing procedure, previously developed by the authors, which involves wetting-drying cycles in water and saline solutions, is employed. Two different types of mortars (based on natural hydraulic lime and Portland cement) were used for the composite matrix, without changing the geometry, the type of masonry substrate and the fibers (galvanized steel cords), in order to assess the role of the matrix in the FRCM-masonry joint bond behavior and deterioration processes. Results show that the matrix played a key role in the debonding mechanism of the FRCM-masonry joints as well as in the capillary absorption of water and in the resulting salt crystallization patterns. [ABSTRACT FROM AUTHOR]

• In this paper, the effects of water–binder ratios and curing ages on the axial tensile stress–strain curves of mortar, new–old mortar interface and RAC were investigated experimentally. • Based on the experimental results and the random aggregate model, the manuscript explores the tensile damage development of RAC and analyzes the law and mechanism of the influence of the properties of old mortar on the axial tensile stress–strain curves of RAC. • In this paper, the tensile constitutive relationship of RAC is proposed based on the tensile constitutive relationship of ordinary concrete, combined with experimental results and numerical analysis results. The tensile constitutive relationship is essential for determining the ductility and restoring force characteristics of seismic-resistant concrete structures and studying the mechanisms causing damage and fracture to concrete structures. This study investigates the axial tensile stress–strain curves of mortar, the interface between new and old mortar, and recycled aggregate concrete (RAC) with different water-binder ratios and ages. First, the tensile constitutive relationships of mortar and new-old mortar interface were established. Then, based on the experimental results and the random aggregate model, a double-interface numerical model of RAC was established to investigate the development of tensile damage in RAC and the influence law and mechanism of the old mortar strength, thickness and curing age on the curve of the tensile stress–strain of RAC. The results are a comparison of the peak tensile strengths at the same age and water-binder ratio for the above three mortar types, where new mortar > RAC > new-old mortar interface. Under the same thickness of old mortar, the peak stress, elastic modulus and peak cutline modulus of RAC increased with the increase of old mortar strength, and the amplitude of change increased with the increase of mortar thickness. Based on the tensile constitutive relationship of ordinary concrete, the tensile constitutive relationship of recycled coarse aggregate concrete is proposed by combining the experimental results and numerical analysis results. [ABSTRACT FROM AUTHOR]

• Mechanical characterization of lime mortars by means of the Drilling Resistance Measuring System (DRMS). • Influence of penetration and rotational speed on drilling results. • Influence of penetration and rotational speed on correlations between UCS and drilling results. • Correlations between the mean of the drilling forces and the depth of cut per revolution. • Comparison between regression models developed using DRMS at a constant and variable depth of cut. The paper investigates the influence of the user-controlled variables on the results of the drilling test (DRMS) performed on lime mortars used for ancient buildings restoration. In particular, the ratio of the penetration and rotational speed (δ), namely the depth of cut per revolution, is considered. The experimental results show a relevant variation in the shapes of the drilling profiles with δ, especially in mortars with lower strengths. The efficacy of the regression models between the uniaxial compressive strength (UCS) and the drilling results changes with the depth of cut. An optimal range of δ to perform the DRMS test is identified for the analyzed mortars. The paper also investigates the possibility of performing the DRMS test according to another procedure poorly studied in the literature to evaluate the UCS of materials. It consists of making more holes in the same material at different values of δ. This method is based on the analytical and experimental results obtained with another scratching technique, the scratch test. The statistical analysis of results shows that the correlation between the mean of the drilling forces and δ can be described by linear regression in a limited range of δ. The slope of the linear regression has a high correlation with UCS. The obtained positive results move to deepen the experimental research on this topic. [ABSTRACT FROM AUTHOR]

In this study, a standard pH test procedure, based on the high alkalinity of electric arc furnace oxidizing slag, was developed for rapid content evaluation of potentially hazardous slag in the fine aggregate and recommended standards are further proposed. The advantages of the developed procedure include easy equipment acquisition, simple test method, short time, and high accuracy. This study found that sample size, water source, and filtrate process were the factors affecting the pH test accuracy. In the test, the pH increased with a decrease in the aggregate size when the proportion of electric arc furnace oxidizing slag in aggregate was fixed, especially when the aggregate size was less than 0.225 mm. Upon comparison of the results of autoclaved mortar bar expansion tests, a good logarithmic relationship was observed between pH and electric arc furnace oxidizing slag content. It is suggested that pH 9.0 could be used as the standard to determine excessive electric arc furnace oxidizing slag in fine aggregate. • Proposed a standardized process for rapidly assessing pH in fine aggregates, addressing hazards from electric arc furnace oxidizing slag (EAFOS). • Optimized pH testing factors: D100 particles, RO water, 10 % solid content, filtration through 5A + 5B paper before measurement. • Sample pH values consistently showed a logarithmic relationship with EAFOS content proportion. • pH values over 9.0 indicate excessive EAFOS content in fine aggregates, making them unsuitable for further application. [ABSTRACT FROM AUTHOR]

In this paper, the method of dehydration condensation reaction was used to establish a superhydrophobic cement mortar surface with the contact angle of 159.3° and the slide angle of 6.1° by using organosilane and inorganic nanomaterials. The nanoparticles built roughness and the silane provided low surface energy, which in combination achieved self-cleaning, waterproof and durability improvement. The superhydrophobic coating with good penetration depth is able to show superhydrophobicity after simply brushing and curing at room temperature for 24 hours and maintain hydrophobicity after surface abrasion. A variety of liquid droplets can roll freely from the surface of superhydrophobic cement mortar and carry contaminants rolling down to show self-cleaning performance. In terms of durability, the coating appears good adhesion to the surface of cement mortar, which retained its hydrophobic property after tape-peeling tests and outdoor simulation tests. In addition, compared with ordinary cement mortar, the superhydrophobic cement mortar demonstrates excellent waterproof ability and freeze-thaw resistance through low water absorption and slow quality reduction after multiple freeze-thaw cycles. These key characteristics provide advantages for concrete protection applications in harsh environments. • A simple method for preparing superhydrophobic surface by brushing chemically-modified liquid is proposed. • The penetration depth of the superhydrophobic coating is 5 mm. • The coating optimizes pore structures and water absorption is reduced by 70.66%. • The coated mortar exhibits pretty icephobic performance and freeze-thaw resistance. [ABSTRACT FROM AUTHOR]

Ammonium carbonate was used as the carbonation accelerator for air-hardening lime mortars in this study. Various analytical methods, including XRD, IR, TGA-DSC and SEM were employed to access the phase transformation, degree of carbonation and microstructural features of the lime-based mortars. The paper explores the correlation between the mechanical strength, microstructure of cured lime mortars and the composition/carbonation degree with the crystallization behaviors in Ca(OH)2/CaCO3 binders. The results indicate that ammonium carbonate significantly accelerates the carbonation reaction and increases the early mechanical strength of air-hardening lime mortars. The mechanical strength of these modified lime mortars can be comparable to that of natural hydraulic lime (NHL). The aggregation behaviors of nano-CaCO3 under kinetic control, are believed to contribute much to the compact pore-structures and robust mechanical strength of lime mortars. This viable accelerating carbonation method holds promise for enhancing the properties of various lime-containing building materials in conservation and modern buildings. • Ammonium carbonate is effective in accelerating the carbonation of aerial lime. • Lime mortars modified by ammonium carbonate rival natural hydraulic lime (NHL). • The mechanical strength is highly related to carbonation degree and pore structure. • Nano-CaCO 3 play pivotal role in compacting the pore structure of lime mortar. [ABSTRACT FROM AUTHOR]

The porous hydrophilic nature of cement-based material is susceptible to water and corrosive media, severely reducing the durability. In this paper, methyl siloxane-based hydrophobic powder was prepared, and its effect on the physicochemical and anti-corrosion properties of mortar with different water-cement ratios were investigated. The results show that the addition of hydrophobic powder significantly improved the hydrophobic properties of mortars. Especially for the mortars with w/c ratios of 0.2 and 0.4, it showed superhydrophobicity with a water contact angle up to 156.5 ° and 152.3 ° respectively. Lower w/c ratio mortar has a denser microstructure, which reduces the water absorption rate of the mortar, and the hydrophobic powder enhances the hydrophobic effect of low w/c ratio mortar more significantly. The methyl siloxane groups in the hydrophobic powders will bind to the C-S-H gel in the mortar through Si-O bonding, preventing the C-S-H gel connections from forming a continuous network structure. This increased the pore volume and reduced the compressive strength by 14.6%-22.7%, but the total hydration degree was increased, and significant corrosion protection of the steel rebar was demonstrated. [Display omitted] • Super hydrophobicity of mortar was achieved by modification of hydrophobic powder. • Hydrophobic mortar with lower w/c ratio exhibits better anti-corrosion performance. • Methylsiloxane groups combine with C-S-H gel by Si-O enhancing hydrophobic properties of mortar. [ABSTRACT FROM AUTHOR]

This study investigated the changes in three characteristics, including phase compositions, microstructure, and microhardness, in the interfacial transition zone (ITZ) of high-ferrite cement (HFC) products when subjected to different curing systems. In addition, we explored the underlying mechanisms through which supplementary cementitious materials (SCMs) influence the ITZ under steam curing conditions. The characterization was performed through the application of test techniques such as X-ray diffraction analysis, backscattered electron, scanning electron microscopy, energy dispersive X-ray spectrometry, and microhardness. The findings demonstrated that the increase in the curing temperatures promoted the HFC mortar to generate an excellent ITZ performance compared to Portland cement and ground granulated blast furnace slag (GGBFS) showed an improvement in steam-cured HFC-ITZ better than. Specifically, optimal enhancement of the ITZ in steam-cured HFC cement-based materials was achieved through the 40% replacement of GGBFS where the calcium hydroxide (CH) content and orientation growth were reduced while the hydration product formation was increased, resulting in declined porosity. Furthermore, the incorporation of 20% replacement of fly ash (FA) led to the decrease in the CH content and porosity of the ITZ. However, due to the lower reaction activity, unreacted FA persisted in the paste even after 28 days of curing. Additionally, the uneven distribution of hydration products resulted in diminished microhardness. On the other hand, a 40% replacement of FA marginally improved the properties of the ITZ. Finally, the test data and conclusions in the paper can provide some evidence for the application of GGBFS and FA in HFC and HFC-based concrete. • At elevated curing temperatures, the ITZ in high-ferrite cement exhibits a denser microstructure. • The steam curing process, combined with a 40% addition of GGBFS, promotes the hydration to enhance the structure of ITZ. • The "filling effect" of FA reduces the porosity of HFC-ITZ, but the lower activity results a lower degree of pozzolanic reaction. [ABSTRACT FROM AUTHOR]

Residential construction materials have undergone a notable evolution within the construction sector. This paper extensively reviews various types of bricks and building materials commonly employed in house construction, categorizing them into classifications such as typical clay, concrete, fly ash, and new materials such as aerated concrete and recycled bricks. The study thoroughly investigates the mechanical, thermal, and environmental potentials of each material, also considering auxiliary building materials like mortar, cement, and bio-materials, which play vital roles in house construction. Its primary objective is to offer valuable insights to architects, engineers, builders, and researchers to facilitate informed decision-making in residential construction projects. It also considers factors such as sustainability and local availability. The research identifies Cellular Lightweight Concrete (CLC) bricks as the optimal choice for residential construction, given their compressive strength of up to 30–40% more than traditional bricks, along with excellent lateral load capacity and displacement ductility, also making them suitable for constructing partition walls. Modifications in composition, such as incorporating coconut and basalt fibres, result in a notable enhancement of approximately 17.4% in thermal insulation with minimal impact on thermal degradation. Ultimately, this review serves as a valuable reference for individuals seeking a deeper understanding of the diverse options available in bricks and building materials for modern residential construction. • Various bricks and building materials for residential construction are reviewed. • Investigate the mechanical, thermal and environmental potential of each material. • Alternative materials like fly ash, mycelium, geopolymer, LTC, and 3D-printed bricks were explored. • Insights into the potential of diverse bricks for sustainable and eco-friendly building practices. • Critically highlight research gaps and provide directions for future studies. [ABSTRACT FROM AUTHOR]

In the underlayment of a floor radiant heating system (FRHS), using gypsum-based self-levelling mortar (GSM) with high fluidity and early strength properties could save labor force and material costs. Combining phase change materials (PCMs) with FRHS is a promising way to improve energy efficiency and provide a comfortable thermal environment. This paper investigates the feasibility of preparing gypsum-based self-levelling energy storage mortar (GSEM) by incorporating fly ash cenospheres/paraffin (FACP) into GSM. The selection of fly ash cenospheres (FAC) particle size, the pre-treatment of FACP, the additional amount of FACP, and the thermal performance of FRHS containing GSEM are investigated. Results show that the selection of FAC should consider the influence of strength, fluidity, thermal property, and possible economic and environmental impacts. FAC 2 with a particle size (D50) of 110.5 µm is considered to be a suitable choice. FACP pre-treated with 52.5 cement could decrease paraffin leakage and increase the mechanical strength and fluidity of GSEM. With the sand replacement ratio (V f) increase, the mechanical strength of GSEM first increases and then decreases. When the V f is 100%, the compressive strength and flexural strength of GSEM are 18.8 MPa and 4.3Mpa; the thermal conductivity decreases by about 15.8% and the specific heat capacity increases by about 53.5%. For FRHS, the matching between the supply water temperature and the plate thickness should be considered in the design. Compared with the GSM plate, the GSEM plate could reduce about 2.4℃ temperature fluctuation, and the time at a comfortable temperature is extended by 60.8%. This finding indicates that the prepared GSEM could be applied to FRHS and has good potential to provide a comfortable thermal environment for buildings. [Display omitted] • Self-levelling mortar containing cenospheres/paraffin is prepared and studied. • Particle size and coating influence the properties of self-levelling mortar. • The mechanical strength of self-levelling mortar meets requirement of standard. • Self-levelling mortar can reduce temperature fluctuation, extend comfortable time. [ABSTRACT FROM AUTHOR]

This paper presents the effect of incorporating wollastonite microfibers and cellulose nanofibers on mechanical properties and microstructure of ultra-high-performance mortar (UHPM). Cellulose nanofibers of 0.005%, 0.015%, and 0.030% are combined with 4.8% wollastonite microfiber by weight of binder, which consists of 10% silica fume and 90% cement. Compressive and flexural strengths of the UHPM specimens are measured at 7 days. The microstructure is characterized in terms of SEM/EDX, XRD, FTIR, and nanoindentation. The results show the effectiveness of the fiber hybridization in enhancing the compressive and flexural strength of ultra-high-performance mortar with the improvement in flexural toughness and fracture energy by as much as 10% than control mortar. Moreover, hybrid fiber-reinforcement based on the microstructural analysis provided more synergic effect and uniform distribution of the fibers, thus developing an efficient micro crack bridging mechanism as well as resulting in enhanced toughening properties and an increased load carrying capacity. Additionally, the combination of wollastonite microfibers and cellulose nanofibers promoted the hydration reaction products and contributed a denser matrix between the fibers and cement matrix, resulting in an increase of the microstructure and interface area between the fibers and cement matrix. Nano indentation analysis also confirmed the increase of UHD C-S-H from 65% to 84% and lower percentage of anhydrous phase in ultra-high-performance matrix after combining wollastonite microfibers and cellulose nanofibers. • The hybridization of cellulose nano fiber with wollastonite microfiber increased the compressive strength of unreinforced mortar. • The greatest advantage in hybrid-reinforcement systems in ultra-high-performance mortar is the improvement in flexural toughness. • Hybrid reinforcement systems develop an efficient crack bridging mechanism as well as resulting in enhanced toughening properties and an increased load carry capacity. • The addition of wollastonite promoted a higher UHD C-S-H compared to the control specimen and other hybrid reinforced mortars. • Cellulose Nano Fibers enhance cement hydration due to the high specific surface area, in addition to the promotion of adhesion with cement paste and bonding properties when combined with wollastonite. [ABSTRACT FROM AUTHOR]

The paper presents the results of studies on based the universal morphology of recycled coarse aggregates in reality, an idealized model of recycled coarse aggregates was prepared using stones. Axial compressive strength tests were conducted on prism-shaped specimens of Modeled Recycled Coarse Aggregate Concrete (MRCAC), which were prepared with different old cement mortar coverages and aggregate arrangements. Through comparison with experimental data, the reliability of the finite element analysis model was determined. It was found that the arrangement of MRCA had a significant impact on the failure characteristics and elastic modulus of MRCAC. Thus, different arrangement modes affected the stress distribution within the specimens, resulting in significantly different axial compressive strength. • Studied the influence of aggregate arrangement on the stress characteristics of MRCAC. • Studied the influence of old cement mortar on the mechanical properties of MRCAC under different internal force transmissions. • Revealed the influence characteristics of old mortar on the stress-strain relationship in recycled concrete. [ABSTRACT FROM AUTHOR]

Applying conductive cement-based anode is one of the commonly used methods to achieve uniform electrochemical protection for concrete structures. However, anodic acidification is a critical challenge limiting the effectiveness of electrochemical protection in concrete. Therefore, carbon fiber (CF) and expanded graphite (EG) were used in the current study as conductive materials to reduce the resistivity of cement-based anode by creating a "multi-scale" conductive grid within the anode, while slag powder was employed to enhance the anode resistance to chloride intrusion. This paper investigated the influence of slag powder on the mechanical properties, resistivity, and hydration products of carbon fiber-expanded-graphite conductive mortar (CECM) anodes. The results indicated an inverse relation between the slag powder content and the mechanical properties and resistivity of cement-based anodes. In general, the optimal dosage of slag powder is 20%, at which the compressive strength and resistivity of CECM decrease by 14.8% and 2.75%, respectively. Furthermore, a cubic function relation could be applied to correlate the slag powder content to the mechanical properties and electrical conductivity of the anodes. CF, EG, and slag powder created a composite structure within the hardened cement paste, and formed a multi-scale conductive grid that reduced the cement mortar's resistivity. Through XRD and FT-IR tests, it was found that during the testing period, the pozzolanic effect of slag powder was insufficient to compensate for the loss of strength resulted from the reduced amount of cement clinker. In addition, TGA-DTG results showed that the total amount of C-S-H in Group A increased from 14.31% to 22.86%, while in the Group B this amount increased from 20.74% to 25.94%. The optimal group had an increase from 20.21% to 24.59% in C-S-H content. These results confirm the similar hydration effect of slag powder on EG cement slurry compared to that on ordinary cement. It also indicates that the chloride ion resistance of cement-based anodes can be enhanced through the pozzolanic effect of slag powder, ultimately achieving long-term stable operation of cathodic protection system. • Slag powder is used to modify CECM. • Slag powder particles distributed in multi-scale conductive grids interlaced with EG and CF. • Quadratic surface can reflect the relation of Slag powder content and CECM's compressive strength and resistivity. • Slag powder's "secondary hydration" does not compensate for the strength loss caused by its "dilution effect". [ABSTRACT FROM AUTHOR]

Radiant floors' performance is highly dependent on the thermal properties of the heat transfer medium embedding the hydronic piping system for heating and cooling, which for wet construction is often a mortar. The objective of this paper is to study the effect that latent heat storage capacity and improved thermal conductivity have on the thermal performance of Radiant Floor Systems (RFS). To that end, two innovative mortars were developed: one incorporating Phase Change Materials (PCM); and another incorporating a dense by-product of the steel industry. The first mortar aims to provide the RFS with thermal energy storage capacity and the later has the goal of improving the mortar's thermal conductivity by incorporating this high-density aggregate into its composition. The methodologic approach comprises the characterization of the thermophysical properties of the mortars developed, as well as the subsequent application of the selected compositions into an experimental RFS apparatus to evaluate the thermal performance under continuous and intermittent heating. The selected mortar incorporating microencapsulated PCM (mPCM) exhibited a mechanical strength loss of 68.1% (compressive strength) and 47.5% (flexural strength) in relation to the reference mortar, thermal conductivity of 0.33 W·m−1·K−1 and specific heat capacity of 1222 J·Kg−1·°C−1. The selected mortar incorporating high-density aggregates revealed a reduction of 16.1% for compressive strength and an increase of 10.0% of flexural strength, in relation to the same reference. Its thermal conductivity resulted of 0.87 W·m−1·K−1 and specific heat capacity of 379 J·Kg−1·°C−1. The thermal behaviour of the RFS specimens revealed the potential of incorporating mPCM into RFS, when intermittent heating relying on night-time operation is adopted, considering the maximum temperature fluctuation of 4.02 °C (PCM-RFS). Mortars with high conductive matrixes portray suitable solutions for quicker thermal responses, exhibiting heating rates of up to 9.6 °C·h−1, if followed by a continuous heating strategy with lower supply water temperatures. • Development of mortar incorporating microencapsulated PCM for radiant floor systems. • Incorporation of steel industry by-product into mortar for increased thermal conductivity. • By-product increased the mortar thermal conductivity and mechanical performance. • PCM resulted beneficial when intermittent heating is used for radiant floor systems. • Mortars with higher thermal conductivity resulted in higher heating and cooling rates. [ABSTRACT FROM AUTHOR]

Sustainability growth in the infrastructure field demands the need for environmentally friendly construction without compromising its structural properties. In this paper, a durable rubberized geopolymer mortar was developed by using the eggshell catalyzation technique. In order to enhance the interfacial bonding of rubber aggregates with the potassium-based geopolymer mortar, the eggshell catalyst was employed as a natural surface modifier. The developed eggshell catalyzed rubber was used to replace 5% by weight of the fine aggregate system and the sustainability of the rubberized geopolymer mortars was studied by assessing the strength and durability characteristics. From the results, it was inferred that the eggshell catalyst transformed the rubber surface into highly hydrophilic and showed a water contact angle of 10°. The trans-esterification process induced by the eggshell-catalyzed rubber aggregates resulted in 10% improved workability and 98.8% recovery in compressive strength of the rubberized geopolymer mortar. Also, due to the formation of secondary gels around the eggshell-catalyzed rubber, the geopolymer mortar becomes denser which prevents the intrusion of foreign ions and showed a 27.9% change in mass under sulphate attack and 33.86 MPa residual compressive strength after 90 days of acid immersion. This attributed the rubberized geopolymer mortar with eggshell catalyzation process to maintain its structural integrity even in the aggressive chemical environment for the feasible applications of deck slab, piers, underground pipe construction, etc. • Sustainable usage of eggshell catalyst for the reuse of rubber aggregates. • Excellent hydrophilicity from trans-esterification reaction. • Cleaner Production of green mortar with eco-friendly alternative aggregate system. • Efficiency of natural surface modifier through aggressive environmental assessment. • 98.8% recovery in strength and maintains structural integrity at chemical exposure. [ABSTRACT FROM AUTHOR]

Recycled aggregate (RA) is a product of construction and demolition wastes, and RA particle presents low strength and adhesion with asphalt mortar compared with natural aggregate. With the aim of studying fracture characteristics of recycled aggregate asphalt concrete (RAAC), the influence of RA on interfacial zone failure should be evaluated. In this paper, RAAC with different RA percentages and gradations were prepared, and a semi-circular bending test (SCB) was employed to assess the fracture behavior of RAAC specimens. Meanwhile, strain distributions during the fracture process were measured by digital image correlation (DIC). To understand the influence of RA on fracture characteristics of RAAC, the microstructural finite element models (FEM) were established, in which natural aggregate and RA particles were reconstructed, respectively. Zero-thickness cohesive zone elements (CZM) were inserted into continuum elements so that the failure of the interface zone between asphalt mortar with different aggregate particles could be investigated. Results indicate that RA presents a significant impact on the fracture response of the asphalt mixture, and the fracture resistance of RAAC attenuates significantly as the RA percentage exceeds 50%. The aggregate-asphalt mortar interface is the first choice in competing fracture paths inside RAAC. The cement mortar-asphalt mortar interface (CAI) exhibited more significant damage than the bulk fracture within the asphalt mortar (AMI) and natural aggregate-mortar interface (NAI). Also, the damage proportion of CMI increases with RA percentage and the maximum nominal particle size of RAAC. This study shows FEM considering different types of interfacial zone provides an effective method to evaluate the fracture characteristics of RAAC. • Low-temperature fracture performance of asphalt mixture containing recycled aggregates was investigated. • The influence of RA on interfacial damage in RAAC under low-temperature fracture was quantified. • The competition mechanism of crack initiation and developing paths inside RAAC was obtained. [ABSTRACT FROM AUTHOR]

To facilitate the use of geopolymer materials in shotcrete applications, this study presents the development of a geopolymer mortar and explores its flowability and early-stage mechanical properties. Firstly, 15 groups of geopolymer mortar specimens with 3 liquid-binder ratios (0.70, 0.75 and 0.80) and 5 binder-aggregate ratios (0.225, 0.250, 0.275, 0.300 and 0.325) were developed. Secondly, the P-wave velocity, slump, early-age compressive strength and compressive strength were obtained by ultrasonic pulse velocity test, slump test and uniaxial compressive test. Thirdly, discussion on the effect of liquid-binder ratio and binder-aggregate ratio on P-wave velocity, flowability, compressive strength and early-age compressive strength of geopolymer mortar were carried out. Finally, an optimal mix proportions rang of geopolymer mortar materials that meet the requirements of wet shotcrete technology were proposed. The results show that P-wave velocity, slump, early-age compressive strength and compressive strength increase as the increasing of liquid-binder ratio. The slump, compressive strength and P-wave increase as the increasing of binder-aggregate ratio. Moreover, the optimal binder-aggregate ratios were proposed as 0.244 - 0.321, 0.228 - 0.298, and 0.209 - 0.241 for geopolymer mortar with a liquid-binder ratio of 0.70, 0.75 and 0.80, respectively. Geopolymer mortar in these mix proportions achieves compressive strengths ranging from 28.4 MPa to 41.1 MPa after curing for 1 day and 44.2 MPa to 55.4 MPa after curing for 28 days. The mix proportion of geopolymer mortar proposed in this paper can simultaneously meet the standard requirements for mechanical properties and flowability, demonstrating potential for wet shotcrete applications. • A mortar for shotcrete application has been developed using geopolymer as the primary material. • The effects of liquid-binder and binder-aggregate ratios on mortar properties were investigated. • Flowability and early-age mechanical properties of the developed mortar were comprehensively analyzed. • An optimal mix proportion range was proposed for effective use in geopolymer shotcrete applications. [ABSTRACT FROM AUTHOR]

Highlights • Effects of glass fiber on mechanical properties of MPC were studied. • The addition of glass fiber improved the water resistance of MPCs. • The flexibility and deformation behavior of MPC can be improved by using glass fiber. • The mechanism of glass fiber improving water resistance of MPC was analyzed. Abstract This paper describes an experimental investigation into the compressive strength, the flexural strength and the water resistance of magnesium phosphate cement (MPC) mortar reinforced by glass fiber. Fiber volume fractions of 1.5%, 2.5%, 3%, 3.5% and binder/aggregate ratios of 1:1, 1:1.2 and 1:1.5 were designed for the experiments. The microstructural, mechanical and water resistance properties of fiber-reinforced MPCs were evaluated with respects to the variance in the fiber volume fraction, the ratio of binder/aggregate. The results showed that the glass fibers have more pronounced effects on the flexural strength compared to compressive strength. The optimum volume fraction of glass fiber is reported at 2.5%. Furthermore, the effect of glass fiber on the water resistance of MPC is discussed, and a "reserving" method to resist the strength loss by water has been proposed. In addition, the paper provides a possible explanation of the fiber reinforcement mechanism which is in agreement with the experimental results. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Patch repairs are widely used for local damage in RC columns. • 15 patch-repaired RC columns were tested at the ICITECH. • The paper analyses the effectiveness of patch repairs on RC columns. • Patch repair is compared with: all-four-sides and one-side repair. Abstract This paper describes an experimental study on patch-repaired reinforced concrete columns subjected to axial loads until failure. The behaviour of four series of columns repaired with Class R3 and R4 cement-based mortar was analysed both with and without a bonding agent. The results obtained were compared with control series of undamaged and damaged but unrepaired columns to determine the effectiveness of the repairs and the subsequent improvement in the behaviour of the columns. The results of this study were compared with those of previous work by the authors on the analysis of all-four-side repairs and one-side repairs. The conclusion reached was that patch repairs are highly effective as compared to the other techniques studied and that using Class R3 mortar achieves better results on damaged columns made with low-quality concrete. It was also concluded that applying a bonding agent does not improve the results, although this element was found to be necessary to prevent the premature detachment of the repair when there is a substantial difference between the stiffness of the column concrete and that of the mortar used in the repairs. [ABSTRACT FROM AUTHOR]

The mechanical response of stone masonry depends on the properties of the components and also on the typology created by the stone units and the mortar joints. While the influence of the component strength on masonry is relatively well studied, few studies have been devoted to its influence on masonry properties mainly because of the difficulty of varying the masonry typology systematically. This paper focuses on generation and calibration of masonry typologies, which serves as foundation for further numerical investigation. To this purpose, we develop a typology generator based on relevant research in computer vision. To characterize different typologies quantitatively, we also develop an objective method to compute the line of minimum trace directly from the image of stone masonry based on graph theory. The code and recommendations for the parameter choices are publicly available online. Altogether, this paper provides a useful tool for researchers to study systematically the influence of historical stone masonry typologies. [ABSTRACT FROM AUTHOR]

This paper discusses masonry buildings constructed in Pernambuco and their relationship to several failures that have occurred, some of which included the death of inhabitants. Topics such as the main features of this building technique and its peculiarities that played an important role in its structural behaviour are discussed in detail. Additionally, the paper presents a large characterization of materials and components used constituting the most important current research on this topic in Brazil. Its content analyses in depth, experimentally, the behaviour of single bricks, prisms and wallets that allow the identification and quantification of the influence of several mortar rendering layers on the load capacity of elements tested. A critical analysis concerning the factors that contribute to the performance observed is presented from which it was possible to realize a significant variability of results. A summary with the main results of all experimental tests is presented. [ABSTRACT FROM AUTHOR]

The heterogeneity of a cement-based material results in a random spatial distribution of carbonation depth. Currently, there is a lack of both experimental and numerical investigations aiming at a statistical understanding of this important phenomenon. This paper presents both experimental and numerical supercritical carbonation test results of cement mortar blocks. The carbonation depths are measured along the carbonation boundary by the proposed rapid image processing technique, which are then statistically studied by calculating, e.g., their probability density and power spectral density (PSD). The results indicate that the distribution of the carbonation depth can be approximately represented by a lognormal distribution function and the PSD has quantitative correlation with some of the statistic parameters used in the simulations. In particular, the effects of the autocorrelation lengths and the coefficient of variation of porosity, which are used to define the random porosity field, on the irregularity of carbonation depth are analyzed numerically in details and validated by experimental results. The study has shown that using a random field of porosity with due consideration of spatial correlation and variance, the irregularity of carbonation depth can be realistically captured by the numerical model. The numerical results confirm that lognormal distributions represent the random nature of carbonation depth well and the average and variance of the irregular carbonation depth increase with the increase of carbonation time, autocorrelation length and coefficient of variation of porosity. The study also offers a potential method to numerically calibrate some of the statistic parameters required by a numerical carbonation model through comparing the PSD with that from experimental tests. Overall the methodology adopted in the paper can provide a foundation for future investigations on probability analysis of carbonation depth and other similar work based on multi-scale and -physics modelling. [ABSTRACT FROM AUTHOR]

In order to promote the resource utilization of phosphorus tailings and reduce carbon emissions of building materials industry, the effects of four kinds of phosphorus tailings with different fineness on the water requirement of cement standard consistency, setting time, cement mortar consistency, mechanical strength and shrinkage properties were discussed in this paper. The concentration of some ions in the leach solution of phosphorus tailings with different fineness was determined. The effects of phosphorus tailings fineness on the hydration process and hydration products of cement were analyzed by heat of hydration, IMP, XRD and SEM. The results show that with the average particle size of phosphorus tailings increasing from 15 µm to 30 µm, the initial setting time of phosphorus tailings cement composite slurry is shortened by 120 min, the consistency of phosphorus tailings cement composite mortar is reduced by 4 mm, and the 28-day compressive strength is reduced by about 8 MPa. The ion concentrations of Ca2+, Mg2+ and F- in the leaching solution increased with the decrease of the fineness of the phosphorus tailings, but the concentration of PO 4 3- ions changed little. Fine phosphorus tailings increase the total amount of heat release from hydration of cement slurry, and promote the emergence of new phase hydration products hydrotalcite minerals. • The dissolution of Ca, Mg, P, and F increases with the decrease of fineness. • Phosphorus tailings delay the hydration of cement. • Fine particles of phosphorus tailings have filling effects and induce nucleation. • The hydrotalcite appeared in the later hydration stage of composite slurry. [ABSTRACT FROM AUTHOR]

Nanomaterial integration in building materials has become a pivotal approach to provide cementitious composites with dual functionality, namely photocatalytic and antimicrobial attributes, conferring self-cleaning and anti-polluting characteristics to these materials. We conducted a systematic literature review on the photocatalytic and antimicrobial properties of ZnO-NP in construction materials, selecting all articles from the last 5 years. We performed a search on the Web of Science and 25 articles were selected consistent with the study purpose, after the filtration process aligned with PRISMA guidelines. This is the first article on this topic using a methodological review, covering all recent literature and the most cited articles from recent decades. Although the volume of articles is still limited, it was possible to identify the most efficient percentages of ZnO-NP in different construction materials (paint, mortar, concrete, wood, others). The main applications, challenges, and themes for future research are discussed to produce safer and more sustainable materials and with potential to be used in the civil construction industry. [Display omitted] • Application of ZnO-NP in building materials is reviewed. • Antimicrobial and photocatalytic potential was summarized. • ZnO-NP helps to creation of building materials that provide safer environments. • This paper aims to encourage and promote the use of ZnO-NP in building materials. [ABSTRACT FROM AUTHOR]

The geometric tortuosity of pores is a critical parameter for assessing the transport characteristics of eroding agents in concrete. Based on the porous, multiphase, and multiscale features of concrete composite materials, this paper establishes a model for geometric tortuosity of pores in concrete composite materials, correlating it with water-cement ratio, volume fraction and shape factor of aggregates, and quantitative analysis is conducted on the influencing factors of tortuosity. The results demonstrate a close alignment between the developed geometric model and experimental results obtained through Mercury Intrusion Porosimetry (MIP). The quantitative analysis reveals that the geometric tortuosity of pores in concrete composite materials increases with an increase in aggregate shape factor and aggregate volume fraction, while it decreases with an increase in water-cement ratio. For instance, as the aggregate shape factor increases from 1.0 to 3.0, the tortuosity of mortar increases from 8.42 to 25.28, and the tortuosity of concrete rises from 10.41 to 93.69. Similarly, as the water-cement ratio rises from 0.2 to 0.6, the tortuosity of hardened cement paste, mortar, and concrete decreases from 13.68, 18.22, and 29.33 to 7.23, 9.42, and 14.76, respectively. Furthermore, an increase in aggregate volume fraction from 0.1 to 0.5 leads to an increase in the tortuosity of mortar from 12.29 to 13.79 and the tortuosity of concrete from 18.08 to 22.76. • A model proposed for the geometric tortuosity of concrete. • A model reflected the time-varying characteristics of concrete microstructure. • A close alignment between the developed geometric model and MIP test results. [ABSTRACT FROM AUTHOR]

In order to better apply basalt powder to supplement cementitious materials (SCMs), this paper chooses the content of basalt powder, fly ash and slag as the influencing factors, and the early strength (3d, 7d) and long-term strength (28d, 60d) of mortar as the evaluation index of SCMs. Based on the response surface and multi-objective optimization method, the Box-Benken experimental design method was used to study the influence of physical and chemical superposition between various factors on the strength development and optimize the ratio.The low-field nuclear magnetic resonance technique was used to detect the water change and porosity difference between the reference group and the optimization group at each age. The results show that the content of stone powder and fly ash has a significant effect on the early and long-term strength, the slag only has a significant effect on the early strength, the interaction between the three has no significant effect on the early and 60 d strength, and the interaction between stone powder and slag has a significant effect on the 28 d strength. The optimal compatibility of basalt stone powder-assisted cementitious materials is stone powder (10%), fly ash (5%), and slag (25.11%). Under this mix ratio, the strength activity index of mortar at each age meets the requirements. In the early hydration process, the physical filling effect of supplement cementitious materials such as stone powder in the optimization group can better optimize the pore structure inside the slurry, and the strength improvement is slower than that of the reference group. In the later stage of hydration, the number of hydration products in the optimized group increased, and the strength increased significantly, which was closer to the strength of the benchmark group. • Rational use of solid waste; • Reduce the amount of cement. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to design a stone filled with cement stabilized macadam (SFCSM) considering shrinkage resistance and easy construction. The corresponding mix proportion design method for SFCSM was proposed. The skeletal coarse aggregates in SFCSM adopt the particle size frequently applied in engineering practice to facilitate construction. In the mix proportion design, the compressive strength test and compaction test were employed to progressively ascertain the optimal blend ratio of coarse aggregates, cement binder, and cement mortar. The vibratory mixing technology (VMT) was introduced to optimize the production of SFCSM. Further, the strength, modulus and shrinkage properties of SFCSM were also evaluated and validated in comparison with the common CSM. The results of the study illustrate that the skeletal coarse aggregates generate the skeletal structure and the role of the filling fine aggregates enhances the stability of the skeletal structure, thus improving the integrity of the mixer. The bonding effect and hydration level of cement in SFCSM is lower than that of the common CSM. The compressive and tensile strength of SFCSM is lower than that of the common CSM. However, the SFCSM has better resistance to dry shrinkage than CSM. The SFCSM as the base is located between the flexible base and the semi-rigid base in the pavement structure design. In addition, the VMT can improve the mixing uniformity of SFCSM and increase its strength. In summary, this study provides inspiration for the shrinkage resistance and practical engineering application of SFCSM. • The mix design method of SFCSM was proposed considering shrinkage resistance and easy construction. • The vibratory mixing technology (VMT) was introduced to optimize the production of SFCSM. • The material properties of SFCSM were evaluated and validated in comparison with ordinary CSM. • The SFCSM has high compressive strength, excellent shrinkage resistance and easy construction. [ABSTRACT FROM AUTHOR]